peters



Ne Mod l.)- r J I A. W.- ROSE.

Electrica l Telephone.

Not 237,132. Patented Feb. 1,1881.

QW\MRALMX Wb N- RETIRE. PNOYMUTHOGRAPNER, WASNINGTON. D. O.

UNITED STATES PATENT OFFICE.

ALLEN W. ROSE, OF NEW YORK, N. Y., ASSIGNOR TO CHARLES A. CHEEVER, OFSAME PLACE; SAID OHEEVER ASSIGNOR TO HIMSELF AS TRUSTEE.

ELECTRICAL TELEPHONE.

SPECIFICATION forming art of Letters Patent No. 237,132, dated February1, 1881.

Application filed October 26, 1880. (No model.)

To all whom it may concern:

Be it known that I, ALLEN W. RosE, acitizen of the Dominion of Canada,residing in the city, county,'and State of New York, have 5 invented acertain new and useful Improvement in TransmittingTelephones,of whichthe following is a specification.

My present invention relates to that class of speaking-telephones-whichembodyin their I organization metallic filings susceptible to magneticor inductive action interposed in -a loose condition in a magnetic fieldin a galvanic circuit. Several forms of such apparatus and its method ofoperation form the sub- I ject-matter of other applications filedsimultaneously with this, and my present claim is therefore limited tothe specific organiza tion shown in the accompanying drawing, whichrepresents a vertical central section through one form of my improvedapparatus.

In this case an ordinary tubular case or handle, 0, provided with theusual mouth-piece, is shown with a magnet, M, secured therein. Aplunger, Q, capable of moving freely end- 2 5 wise in the guideway ofsaid casing, is located near the mouth-piece, being preferably supportedand kept from contact with the magnet M by means of suitable buffers orsprings b, thus leaving a cavity or chamber between 0 them, constitutinga magnetic field, in which are placed metallic filings in a loosecondition. This plunger must be a conductor of electricity, but need notnecessarily be a magnet. The filings may be ofiron, steel, aluminium,cobalt,

5 nickel,or other metal capable of inductive action; butthelast-mentioned metalis preferable, as it does not rust on exposure tomoisture.

These filings may be in the form of a coarse powder; but I prefer to usethem in the form of slivers or filings the length of which is 4.0 threeor four times greater than their width or thickness.

A mixture of filings of different magnetic metals or filings and powderof similar or dissimilar magnetic metals may be used. 5

Either a permanent or electro magnet may be employed.

The wire W connects the spindle or magnet M with one pole of the batteryand the wire W connects the plunger with the other pole, thus includingthem, as well as the interposed filings, in a magnetic field in anordinary galvanic circuit, the normal condition of the filin gs, andconsequently their conductive capacity, being varied by vibrationscaused by the impingement of sound-waves directly upon the plunger,consequently producing correspond ing variations in the strength of acurrent traversing the circuit, as is well understood.

I claim herein as of my own invention- The combination, substantially asherein set forth, of the case, the magnet, the plunger, the interposedbuffers or sustaining-springs, and metallic filings susceptible toinductive or magnetic action in a magnetic field, and constituting partof a galvanic circuit.

In testimony whereof I have hereunto subscribed my name this 22d day ofOctober, A. D. 1880.

A. W. ROSE.

Witnesses:

WILLARD L. (JANDER, E. G. DAVIDSON.

